In the art of printing, inks which can be efficiently used on all surfaces have long been sought. Generally speaking, the more cumbersome printing processes such as screen printing, hot stamping, and rotogravure have been required where it is desired to print on non-porous surfaces. High speed economical processes such as lithography have not proven dependable on such surfaces. In Leach et al., The Printing Ink Manual, Van Nostrand Reinhold (International) Co., Ltd., 4th Ed. (1988) on page 310, it is noted that: ". . . the main use of litho printing is on paper and board substrates. Attempts to formulate a wide range of wholly satisfactory inks for film, plastics, and foil substrates are impeded by litho restrictions. This is not to say that such materials cannot be printed by lithography, but achieving full ink adhesion on the stock is often more problematic than with gravure, screen, or flexo systems."
Overcoming the problem of adhesion on all stocks would obviously be desirable so that a particular printing installation could treat all types of substrates. The major difficulty has been to formulate an ink which effectively adheres to non-porous substrates. In addition, it is desirable to have inks which can be applied as a thin film, dry quickly upon application, and also possess the apparently contradictory property of slow deep drying so that they will not clog printing equipment by drying on the parts of the press prematurely. To achieve these ends, it is desirable to minimize the use of lithographic ink solvents which are added to inks to obtain the necessary low viscosity. Solvents prevent the high loading of solids, therefore requiring the application of thicker films to the substrate to gain the necessary opacity. Also, solvents are increasingly an environmental problem and, while they improve the flow properties, they impede the drying process.
Inks meeting these criteria have heretofore not been attainable.
Certain efforts have been made to increase the pigment loading of inks by the addition of organo-titanate compounds. The use of organo-titanates and/or organo-zirconates in paints and other coating compositions has been described in the literature.